Standby

Waiting at the airport for a seat on a flight you do not hold — mostly limited these days to same-day changes on your own carrier, under fees and rules that vary by fare and status. In premium cabins standby is a narrow tool: same-day confirmed changes (a defined fee for a guaranteed seat on an earlier flight) are the version worth knowing, while open-ended standby across carriers belongs to a previous era of flying. Where your fare allows same-day flexibility, the quote says so.